Impact clutch with sliding key in anvil



Sept. 28, 1965 c. A. ADEE 3,208,569

IMPACT CLUTCH WITH SLIDING KEY IN ANVIL Filed Jan. 16, 1963 EL a 14 c A. ADEE, DEC ED, BY CLA RY ADEE, EXECUTRIX BY I ATTORNEY United States Patent 3,208,569 IMPACT CLUTCH WITH SLIDING KEY IN ANVIL Chester A. Adee, deceased, late of Port Washington, N.Y.,

by Clarice Berry Adee, executrix, Hicks Lane, Sands Point, Port Washington, N.Y.

Filed Jan. 16, 1963, Ser. No. 252,280

4 Claims. (Cl. 192-305) This invention relates to impact clutches and more particularly to that type of clutch adapted for use in tools wherein a hammering element is adapted to deliver rotatively directed blows to an anvil to rotate a wrench socket or other implement.

As tools of this character have been constructed heret-ofore, the construction has been complicated, partly because the striking jaws of the hammer have been mounted to reciprocate in a massive hammer body. Commonly the jaws form part of a heavy spider sliding in guides on the main part of the hammer. Furthermore, the hammer jaw assembly, being heavy, has the effect of transmitting a longitudinal jiggling which makes the tool uncomfortable and hard to handle.

By this invention the part which intermittently keys the hammer to the anvil can be relatively light, requiring relatively little power to reciprocate it so that it is more responsive. In addition, the keying member can be of relatively small section and, as it is mounted perpendicularly with respect to the hammer jaws which engage it, there is substantially no bending moment in the key. The stress is practically all sheer.

By this construction also, part-s which actuate the key or anvil jaw have a tendency to take up the slack between surfaces which transmit and receive the force of the impact.

It is accordingly an object of this invention to provide a simple, reliable and cheaply manufactured and maintained impact wrench.

Further objects and advantages of the invention will be in part obvious and in part pointed out hereinafter.

In the drawing which illustrates a preferred form of the invention:

FIGURE 1 is a longitudinal section of the fore part of a tool embodying the invention, taken along the line ll of FIGURE 2 looking in the direction of the arrows,

FIGURE 2 is a cross section taken along the line 2-2 of FIGURE 1 looking in the direction of the arrows,

FIGURE 3 is a cross section taken along the line 3-3 of FIGURE 1,

FIGURE 4 is a longitudinal section through the portion of the anvil, the anvil jaw or key and the actuating cam for said jaw, and

FIGURE 5 is a cross sectional view of an alternative form of drive connection between the stem of the actuating cam and the hammer body.

Referring to the drawings, the impact clutch includes a massive hammer rotatable within a suitable cylindrical hammer casing 12 and adapted to deliver impact blows to a rotatable anvil 14. The anvil 14 is provided with a sleeve type bearing 16 in the nose 18 of the casing [12 and may have a square end 20 to receive a socket wrench 22 or other suitable implement held on the end '20 by means of a retaining pin 24. The anvil 14 is provided with a stem portion 26 and a head in the form of a circular flange 2'8 which is adapted to bear against a flange B0 of sleeve bearing .16. The hammer 10 is provided at its rear end with a hollow stub shaft 32 I0- tatably supported by suitable anti-friction ball bearings 34 carried by the front wall 36 of motor casing 38 to the periphery of which the casing 142 is secured. lAny suitable type of motor may be used for driving the hammer 10. The motor is provided with a shaft 40 having a suitable key 42 within stub shaft 32 for connection of the motor to the hammer. Inasmuch as the motion of hammer 10 will be principally intermittent, since the driving connection to the motor is rigid in this case, the motor (not shown) is preferably operated by motive fluid such as compressed air or the like. I

The front end of hammer 10 is provided with at least one jaw 44. In the embodiment illustrated in the drawings there are three jaws angularly spaced apart about the axis of the rotor. Preferably anvil 14 and hammer 10 are coaxial and the front faces of jaws 44 may if desired rest on, -or at least be in close proximity to, the rear face 46 of anvil head 28. For centering hammer '10 with respect to anvil 14, any suitable means may be provided as will occur to those skilled in the art. method of such centering is to provide forward extensions 48 of jaws 44 which encircle the cylindrical perip'hery 50 of anvil head 28. Coupling of anvil 14 with hammer 10 is accomplished by means of at least one key element 52 carried by anvil 14 and adapted to be intermittently projected into the path of hammer jaws 44 to be struck thereby. In this instance, there are three such key elements 52 which may be termed jaws and they are spaced at angularity with respect to each other about the axis of anvil 14. Jaws '52 are joined at the center by a tubular portion 54 which is adapted to slide in a bore 5 6 of anvil 14 and is coaxial therewith. Keys 52 are adapted to slide in closely fitting radial slots 58 formed in the anvil head 28 and extending from the rear face 46 part way into the head. In their withdrawn position, the jaws 52 should preferably lie below the face 46 of anvil 14 so as to permit jaws 44 to pass unobstructed over them. Preferably jaws 52 are slightly narrower than jaws 44 so that in no case will jaws 44 be able to enter slots 58. Normally jaws 52 are withdrawn within slots 58 due to the pressure of resilient means, in this instance a coil spring 60 disposed in a central bore 64 axially provided in hammer 10 and pressing against the face of jaws 52 at the tubular portion 54 and a thrust bearing 62 interposed between spring 60 and the end of the bore '64.

Jaws 52 are intermittently or periodically projected part way out of slots 58 by means of a cam 66 having a stem 68 extending through tube 54 and encircled by spring 60. The cam 66 is driven in timed relationship by drive shaft 40 through the medium, in this instance, of hammer '10 which is provided with a square hole 69 to receive a squared end 70 of stem 68. As shown in FIG- URE 4, a rise 71 of cam 66 is adapted to co-operate with a similar raised cam following surface 72 on tube 54. If the tool is to be operative both right hand and left hand, the high points 711 and 712 of the parts 54 and 66 should contact when anvil jaws 52 are midway between hammer jaws 44. Since cam surfaces 71 and 70. are in this instance adapted to raise jaws 52 only once per revolution of hammer 10, jaws 52 will have to be raised rather suddenly so as to avoid striking the hammer jaws 44 as they rise as well as when they fall. The required sudden rise, and in fact late rise, may be accomplished by the connection for cam stem 68 and hammer 10 shown in FIGURE 5 in which straight flutes 74 formed in hamrner .10 will engage similar flutes 76 formed on the end of cam stem 68. This will allow plenty of time for raising jaws 52 with relatively short cam risers 711 and 72. (Because of the looseness provided between llutes 74 and 76, the action will be similar regardless of the direction of turning of hammer 10. The timing of cam 66 with respect to jaws 5 2 should be such that jaws 52 will rise to the uppermost position shortly before being struck by hammer jaws 44 and at the moment of striking of the Patented Sept. 28, 1965 A simple jaws, the cams should be completely free of each other, or nearly so. In any case, the two top points of the cam 71 and cam follower 72 should be passed each other. If the connection shown in FIGURE 5 is used, the inertia of jaws 52 will ordinarily sufifice to maintain them in position to be struck by hammer jaws 44. With the looseness of the connection as shown in FIGURE 5, spring 64 will in any case return jaws 52 even if cam 66 has to be reversed in its rotational direction by the reverse camming action of the cams surfaces 71 and 72. Time for such action is provided because the obstruction presented by jaws 52 to hammer jaws 44 will stop relative rotation of the anvil 14 and hammer '10.

It will be seen that the resistance to rising of stem 68 due to the compressive force of spring 60 will cause a slight rotative tendency of jaws 52 which will take up the slack between those jaws and the slots 58 as well as any looseness in the fit of the squared end 20 of anvil 14 and socket 22. Thus, the impact of hammer against anvil 14 will be relatively solid. If desired, friction between the bottom of bore 55 and the cam 66 may be reduced by the provision of a ball bearing 80 seating in a depression 82 in anvil stem 26 and a depression 84 formed in the end of cam 66. The ball bearing however, may be dispensed with if it is desired to take advantage of this friction for additional snubbing.

As tools of this character operate, the rate of rotation is more or less rapid depending upon, and varying with, the size of the tool. In general, it may be said that a higher speed of the hammer permits the use of a hammer of less weight. Since, in its operation, the hammer may be said to come to a standstill and then accelerate to a high speed, reaching maximum speed at the moment of impact, it is generally preferable to strike not more than one blow per revolution of the hammer. Thus, the hammer can accelerate to a suitable speed without the use of a heavy and powerful driving motor. In some instances it may be desirable to use a smaller motor and a smaller hammer and produce impacts less often than once per blow. This can be regulated by suitable driving connections of the cam 66. Such higher speed will be additionally useful as it will prolong the relative delay above referred to due to the inertia of the anvil jaws 52.

Thus, by the above construction are accomplished among others the objects hereinbefore referred to.

What is claimed is:

1. An impact clutch comprising a casing, a hammer rotatable in said casing, means for driving said hammer in rotation, said hammer having an axial bore opening at a forward end of the hammer and at least one longitudinally projecting jawon said forward end, an anvil rotatable in said casing adjacent the forward end of said hammer and coaxial therewith, said anvil having an axial bore opening at a rear face thereof and at least one slot extending radially from said bore, a key having a tubular portion received in said bore of the anvil and at least one jaw received in said radial slot, said key being movable axially of said anvil between an active position in which said jaw of the key is engageable by said jaw of the hammer and an inactive position in which said key is retracted out of engagement by said hammer, a stern extending longitudinally of said bores, means providing a driving connection between said stem and hammer, cooperating cam means on said tubular portion of the key and a forward end portion of said stern for moving said key to active position and a spring encircling said stem and acting between said hammer and key to bias said key to inactive position, said key being moved intermittently to active position by said cam means to bring said jaw of the key into this path of travel of said jaw on said hammer whereby said jaw of the key is engaged by said jaw of the hammer to impart rotary movement to the anvil.

2. An impact clutch comprising a casing, a hammer rotatable in said casing, means for driving said hammer in rotation, said hammer having an axial bore opening at a forward end of the hammer and a plurality of angularly spaced longitudinally projecting jaws on said forward end, the spaces between said jaws being of greater angular extent than said jaws, an anvil rotatable in said casing adjacent the forward end of said hammer and coaxial therewith, said anvil having a forward stem portion and a rearward head portion of greater diameter than said stem portion and having an axial box opening in said head portion and a plurality of slots in said head portion extending radially from said bore in the anvil, said slots having a lesser radial extent than the spaces between said jaws of the hammer, a key having a tubular portion received in said bore of the anvil and a plurality of radial jaws received in said radial slots, said key being movable axially of said anvil between an active position in which said jaws of the key are engageable by said jaws of the hammer and an inactive position in which said key is retracted out of engagement by said hammer, a stem extending longitudinally of said bores, means providing a driving connection between a rear end of said stem and said hammer, cooperating cam means on a forward end portion of said stem and said tubular portion of the key for moving said key to inactive position upon predetermined rotary movement of said stern relative to said anvil and a spring encircling said stem and acting between said hammer and key to bias said key to inactive position.

3. An impact clutch according to claim 2, in which said drive means for said stern provide a lost motion driving connection between said hammer and stem.

4. An impact clutch according to claim 2, in which a low friction thrust bearing is provided at one end of said spring to transmit axial thrust without rotational torque.

References Cited by the Examiner UNITED STATES PATENTS 1,855,456 4/32 Miller 192-305 2,825,436 3 /58 Amtsberg 19230.5 2,903,111 9/59 Young 19230.5

DAVID J. WILLIAMOWSKY, Primary Examiner. 

1. AN IMPACT CLUTCH COMPRISING A CASING, A HAMMER ROTATABLE IN SAID CASING, MEANS FOR DRIVING SAID HAMMER IN ROTATION, SAID HAMMER HAVING AN AXIAL BORE OPENING AT A FORWARD END OF THE HAMMER AND AT LEAST ONE LONGITUDINALLY PROJECTING JAW ON SAID FORWARD END, AN ANVIL ROTATABLE IN SAID CASING ADJACENT THE FORWARD END OF SAID HAMMER AND COAXIAL THEREWITH, SAID ANVIL HAVING AN AXIAL BORE OPENING AT A REAR FACE THEREOF AND AT LEAST ONE SLOT EXTENDING RADIALLY FROM SAID BORE, A KEY HAVING A TUBULAR PORTION RECEIVED IN SAID BORE OF THE ANVIL AND AT LEAST ONE JAW RECEIVED IN SAID RADIAL SLOT, SAID KEY BEING MOVABLE AXIALLY OF SAID ANVIL BETWEEN AN ACTIVE POSITION IN WHICH SAID JAW OF THE KEY IS ENGAGEABLE BY SAID JAW OF THE HAMMER AND AN INACTIVE POSITION IN WHICH SAID KEY IS RETRACTED OUT OF ENGAGEMENT BY SAID HAMMER, A STEAM EXTENDING LONGITUDINALLY OF SAID BORES, MEANS PROVIDING A DRIVING LONGITION BETWEEN SAID STEM AND HAMMER, COOPERATING CAM MEANS ON SAID TUBULAR PORTION OF THE KEY AND A FORWARD END PORTION OF SAID STEM FOR MOVING AND KEY TO ACTIVE POSITION AND A SPRING ENCIRCLING SAID STEM AND ACTUATING BETWEEN SAID HAMMER AND KEY TO BIAS SAID KEY TO INACTIVE POSITION, SAID KEY BEING MOVED INTERMITTENTLY TO ACTIVE POSITION BY SAID CAM MEANS TO BRING SAID JAW OF THE KEY INTO THIS PATH OF TRAVEL OF SAID JAW ON SAID HAMMER WHEREBY SAID JAW OF THE KEY IS ENGAGED BY SAID JAW OF THE HAMMER TO IMPART ROTARY MOVEMENT OF THE ANVIL. 